I'm not in Mn, but.......
It looks like that unless you're making IRA withdrawals and requesting zero state withholding, you don't need to do anything.
If you are making IRA withdrawals with zero state withholding, and want to continue doing so, you'll have to submit this form. Call Vanguard and ask about the Tx address or ask for instructions on how to submit it securely via their website.
This is one of those rare cases where in similar situations I appreciate the local Schwab B and M office. I'd call my rep and find out what's up. If it's legit and applies to me, he would take care of the downloading, printing, filling out, etc., and just have me stop by, review and sign it.